1. Field of the Invention
The present invention relates to heat sink assemblies, and particularly to heat sink assemblies with adjustable clips which can provide adjustable pressure acting on heat sinks.
2. Related Art
Computer electronic devices such as central processing units (CPUs) frequently generate large amounts of heat, which can destabilize operation and cause damage. A heat sink placed in thermal contact with an electronic device transfers heat from the electronic device through conduction. Modem heat sinks are being made larger and heavier. Therefore, a back plate is often attached on an underside of a motherboard below an electronic device mounted on the motherboard. The back plate reinforces the motherboard.
U.S. Pat. No. 6,141,220 discloses a heat sink assembly comprising a mother board, a back plate attached below the mother board, a heat sink attached on the mother board, and a pair of clips. The back plate comprises four upright mounting rods. Each of the rods has a narrowed neck. Each clip has a pair of spring strips extending obliquely upwardly. Each spring strip defines a slot. The rods sequentially extend through holes defined in the motherboard and the heat sink to engage in the slots of the corresponding spring strips. Each clip is integrally made from a sheet of metallic material. Therefore the fixing force of the clips cannot be adjusted to fit heat sinks of varying sizes and weights. Accordingly, the clips are not easily interchangeable for use in various applications.
Accordingly, an object of the present invention is to provide a heat sink assembly having a clip which can provide adjustable pressure acting on a heat sink.
To achieve the above-mentioned object, a heat sink assembly in accordance with the present invention comprises a heat sink, a back plate, and a clip. The heat sink is attached on a CPU, which itself is mounted on a motherboard. The back plate is attached below the motherboard. A pair of posts of the back plate extends through the motherboard and the heat sink. The heat sink includes a base and a plurality of fins. A longitudinal channel is transversely defined through a middle of the fins. The base defines a recess below and in communication with the channel. An annular disc having a recessed portion is fittingly received in the recess. The clip includes a pressing portion received in the channel, and a pair of locking portions engaging with the corresponding posts. A bolt is screwed through the pressing portion to abut against the recessed portion of the disc. By adjusting a depth to which the bolt is screwed through the pressing portion, the clip can provide adjustable pressure acting on the heat sink. Thus the heat sink can firmly contact the CPU with minimal risk of damage being caused by excessive pressure.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention with attached drawings, in which: